for-loop

import java.util.Scanner;
public class forLoop {
    public static void main(String[] args){
//        // TODO: 1-Simple loop to print numbers from 1 to 5
        for(int i = 1; i <= 5; i++) {
            System.out.println("Welcome to java programming");
            System.out.println(i);
        }
//        /* ------------------------------------------------------- */
//        // TODO: 2-Loop to print numbers in reverse order from 5 to 1
        for (int i = 5; i >= 1; i--) {
            System.out.println(i);
        }
//        /* ------------------------------------------------------- */
//        // TODO: 3-Loop to print even numbers from 2 to 10
        for (int i = 2; i <= 10; i++) {
            if (i % 2 == 0) {
                System.out.println(i);
            }
        }
//        /* ------------------------------------------------------- */
//        // TODO: 4-Loop to print numbers from 1 to 10, skipping multiples of 3
        for (int i = 1; i <= 10; i++) {
            if (i % 3 != 0) {
                System.out.println(i);
            }
        }
//        /* ------------------------------------------------------- */
          /* TODO: 5-Loop to calculate the sum of numbers from 1 to 100
              (skip multiples of 5)
          */
        int sum = 0;
        for (int i = 1; i <= 100; i++) {
            if (i % 5 != 0) {
                sum += i;
            }
        }
        System.out.println("Sum: " + sum);
//        /* ------------------------------------------------------- */
            /* TODO: 6-Write a program in Java to input 5 numbers from the
                keyboard and find their sum and average
            */
        float kk,n=0,s=0;
        double avg;
        System.out.println("Input the 5 numbers : ");
        Scanner in = new Scanner(System.in);
        for (kk=0; kk<5; kk++)
        {
            n = in.nextInt();
            s +=n;
        }
        avg=s/5;
        System.out.println("The sum of 5 no is : " +s+"\nThe Average is : " +avg);
//        /* ------------------------------------------------------- */
//        // TODO: 7-Loop to calculate the factorial of a number
        // example 5! = 5×4×3×2×1 = 120
        int nn = 5;
        int factorial = 1;
        for (int j = 1; j <= nn; j++) {
            factorial *= j;
        }
        System.out.println("Factorial of " + nn + ": " + factorial);
//        /* ------------------------------------------------------- */
//        // TODO: 8-Loop to print the Fibonacci series (each number is the sum of the two preceding ones)
        int nf = 8;
        int a = 0, b = 1;
        System.out.print("Fibonacci Series: ");
        for (int x = 1; x <= nf; x++) {
            System.out.print(a + " ");
            int sum1 = a + b;
            a = b;
            b = sum1;
        }
//        /* ------------------------------------------------------- */
//        /* TODO: 9-Loop to find and print prime numbers
//        (only divisible by itself and one) between 1 and 20 */
        for (int i = 2; i <= 20; i++) {
            boolean isPrime = true;
            for (int j = 2; j < i; j++) {
                if (i % j == 0) {
                    isPrime = false;
                    break;
                }
            }
            if (isPrime) {
                System.out.println(i);
            }
        }
//        /* ------------------------------------------------------- */
//        // TODO: 10-Nested loop to create a pattern
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print("* ");
            }
            System.out.println();
        }
//        /* ------------------------------------------------------- */
//        // TODO: 11-Loop to print a pyramid pattern
        int n3 = 4;
        for (int i = 1; i <= n3; i++) {
            for (int j = 1; j <= n3 - i; j++) {
                System.out.print("  ");
            }
            for (int k = 1; k <= 2 * i - 1; k++) {
                System.out.print("* ");
            }
            System.out.println();
        }
//        /* ------------------------------------------------------- */
//        // TODO: 12-Loop to print a square pattern
        int size = 5;
        for (int i = 1; i <= size; i++) {
            for (int j = 1; j <= size; j++) {
                System.out.print("* ");
            }
            System.out.println();
        }
//        /* ------------------------------------------------------- */
//        // TODO: 13-Loop to print numbers in a triangular pattern
        int rows = 5;
        int count = 1;
        for (int i = 1; i <= rows; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(count++ + " ");
            }
            System.out.println();
        }
//        /* ------------------------------------------------------- */
//        // TODO: 14-Loop to find and print the sum of even numbers in a given range
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the start of the range: ");
        int start = scanner.nextInt();

        System.out.print("Enter the end of the range: ");
        int end = scanner.nextInt();

        int sum3 = 0;
        for (int i = start; i <= end; i++) {
            if (i % 2 == 0) {
                sum3 += i;
            }
        }
        System.out.println("Sum of even numbers in the range " + start + " to " + end + ": " + sum3);
//        /* ------------------------------------------------------- */
//        // TODO: 15-Loop to calculate and print the factorial of a number entered by the user
        System.out.print("Enter a number: ");
        int n2 = scanner.nextInt();

        int factorial2 = 1;
        for (int i = 1; i <= n2; i++) {
            factorial2 *= i;
        }
        System.out.println("Factorial of " + n2 + ": " + factorial2);
        scanner.close();
        /* ------------------------------------------------------- */
        // TODO: 16-Salary Calculation System for Multiple Employees

        System.out.print("Enter the number of products in the inventory: ");
        int numberOfProducts = scanner.nextInt();
        scanner.nextLine();

        double totalInventoryValue = 0;

        for (int i = 1; i <= numberOfProducts; i++) {
            System.out.println("\nProduct #" + i);

            System.out.print("Enter product name: ");
            String productName = scanner.nextLine();

            System.out.print("Enter product price: ");
            double productPrice = scanner.nextDouble();

            System.out.print("Enter quantity in stock: ");
            int productQuantity = scanner.nextInt();
            scanner.nextLine();

            double productValue = productPrice * productQuantity;

            totalInventoryValue += productValue;

            System.out.println("Product Name: " + productName);
            System.out.println("Price per Unit: $" + productPrice);
            System.out.println("Quantity in Stock: " + productQuantity);
            System.out.println("Total Value of Product: $" + productValue);
        }

        System.out.println("\nTotal Value of Inventory: $" + totalInventoryValue);
        /* ------------------------------------------------------- */
        // TODO: 17-Salary Calculation System for Multiple Employees
        System.out.print("Enter the number of employees: ");
        int numberOfEmployees = scanner.nextInt();

        for (int i = 1; i <= numberOfEmployees; i++) {
            System.out.println("\nEmployee #" + i);

            System.out.print("Enter the number of hours worked: ");
            double hoursWorked = scanner.nextDouble();

            System.out.print("Enter the hourly rate ($): ");
            double hourlyRate = scanner.nextDouble();

            // Calculate gross salary
            double grossSalary = hoursWorked * hourlyRate;

            // Deduct tax (10%) and insurance ($50)
            double taxDeduction = grossSalary * 0.10;  // 10% tax
            double insuranceDeduction = 50;  // Flat $50 for insurance

            double netSalary = grossSalary - taxDeduction - insuranceDeduction;

            System.out.println("Gross Salary: $" + grossSalary);
            System.out.println("Tax Deduction (10%): -$" + taxDeduction);
            System.out.println("Insurance Deduction: -$" + insuranceDeduction);
            System.out.println("Net Salary: $" + netSalary);
        }
        /* ------------------------------------------------------- */
        // TODO: 18-student grading system
        System.out.print("Enter the number of subjects: ");
        int numSubjects = scanner.nextInt();

        double totalMarks = 0.0;
        double totalWeight = 0.0;

        for (int i = 1; i <= numSubjects; i++) {
            System.out.print("Enter the weight for subject " + i + ": ");
            double weight = scanner.nextDouble(); // Get weight for the current subject
            System.out.print("Enter the marks for subject " + i + ": ");
            double marks = scanner.nextDouble(); // Get marks for the current subject

            // Add weighted marks to the total
            totalMarks += marks * weight;
            totalWeight += weight;
        }

        // Calculate weighted average
        double weightedAverage = totalMarks / totalWeight;

        String grade;
        if (weightedAverage >= 90) {
            grade = "A";
        } else if (weightedAverage >= 80) {
            grade = "B";
        } else if (weightedAverage >= 70) {
            grade = "C";
        } else if (weightedAverage >= 60) {
            grade = "D";
        } else {
            grade = "F";
        }

        System.out.println("\nTotal Weighted Marks: "+ totalMarks);
        System.out.println("Total Weight: "+ totalWeight);
        System.out.println("Weighted Average: "+ weightedAverage);
        System.out.println("Final Grade: " + grade);

//         TODO:-----------------break and continue--------------------
        int userInput;
        while (true) {
            System.out.print("Enter a positive number (or -1 to exit): ");
            userInput = scanner.nextInt();
            if (userInput == -1) {
                System.out.println("Exiting the program.");
                break;
            }
            if (userInput <= 0) {
                System.out.println("Invalid input. Please enter a positive number.");
                continue;
            }
            System.out.println("Valid input received: " + userInput);
        }
        scanner.close();
    }
}